I think if you want a better education it's best to go to a private school becuase classes are usually smaller granting more attention towards each individual student. However I don't think a private school is the best choice for someone to develop mentally and socially. In a private school students are usually protected to a very high degree from negative attention and are restricted from socializing which can lead to social "defects" and inability to handle certain situations where as a public school student is subjected to bullying and need for socializion which helps them to develop.
Also I don't think the government should fund private schools becuase public schools are already underfunded as it is.
My opinion of all girls/boys schools is that it wouldn't be a very wise decision to send your kid to one for the sole reason that the opposite sexes need to be exposed to eachoter early on and regularly so that they can learn how to react to one anoter accordingly.